Warning: That $20 junction box nearly started a fire in my basement

I was installing a ceiling fixture in my house last week and grabbed a plastic box from the big box store. After wiring it up, I flipped the breaker and heard a faint crackling sound. Turned out the box wasn't rated for the heat of the dimmer switch I used, and the plastic started melting. I swapped it for a metal box after a guy at the supply house in Akron told me to check the UL listing. Has anyone else had a near miss with a cheap box?

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2 Comments

the_julia4mo ago

Plastic boxes are fine if you match the rating. User error, not the box.

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webb.jordan4mo ago

@the_julia's right that ratings matter, but the problem is most people don't realize those cheap plastic boxes have way lower heat limits than the metal ones. A dimmer switch can easily hit 120 degrees inside a closed box, and those 50-cent plastic jobs aren't built for that kind of heat over time. Just because it passed some test in a lab doesn't mean it's safe in your actual basement with all the other variables.

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